A bottom support for controlling deformation of surrounding rock of a traffic tunnel and a method for determining parameters of the bottom support

Abstract

The application belongs to the technical field of surrounding rock support, and specifically discloses a bottom support for controlling deformation of surrounding rock of a traffic tunnel and a parameter determination method thereof. The bottom support comprises a pier wall part in contact with the surrounding rock of the side wall of the traffic tunnel, and the cross section of the pier wall part is a right trapezoid. The parameter determination method of the pier wall part comprises the following steps: presetting the height of the pier wall part, and determining the pressure borne by the surrounding rock of the side wall of the traffic tunnel according to the height of the pier wall part and the chamber height of the traffic tunnel; determining the shearing force applied by the surrounding rock of the side wall to the pier wall part according to the safety factor of the traffic tunnel and the pressure borne by the surrounding rock of the side wall; determining the overturning moment applied by the surrounding rock of the side wall to the pier wall part according to the height of the pier wall part and the shearing force; and determining the upper base width and the lower base width of the pier wall part according to the shearing force and the overturning moment. The parameter determination method can determine the optimal size parameters of the pier wall part, so that the traffic tunnel can be stably supported, the use of the traffic tunnel is not affected by the bottom support, and the construction cost can be saved.

Description

Technical Field

[0001] The invention belongs to the technical field of surrounding rock support and discloses a bottom support for controlling deformation of surrounding rock of a traffic tunnel and a method for determining its parameters. Background Art

[0002] When penstocks are installed in the lower level section of a hydropower project's diversion tunnel, a temporary access tunnel is excavated perpendicular to the tunnel to transport the penstocks. Due to the tunnel's large diameter and open space on both sides, the surrounding rock undergoes significant unloading and relaxation, leading to significant deformation of the surrounding rock walls and cracking of the sprayed layer. Therefore, support measures are necessary for the surrounding rock of the access tunnel.

[0003] Due to limitations in construction conditions and excessive surrounding rock deformation, traditional support measures such as anchor rods, cables, anchor plates, and steel arches cannot be used in traffic tunnels. Specifically, anchor rods, cables, and anchor plates are difficult to resist large deformations; the installation and fixing of steel arches require high technology, equipment, and on-site space, and are difficult and costly to construct. Summary of the Invention

[0004] The purpose of the present invention is to provide a support for controlling the deformation of the surrounding rock of a traffic tunnel and a method for determining its parameters, so as to solve the technical problem that existing support measures are difficult to apply in traffic tunnels due to limitations such as construction conditions and excessive deformation of the surrounding rock.

[0005] A first aspect of the present invention provides a method for determining parameters of a support for controlling deformation of surrounding rock in a traffic tunnel. The support includes a pier wall portion connected to the side wall surrounding rock of the traffic tunnel. The cross-section of the pier wall portion is a right-angled trapezoid. The method for determining the parameters of the pier wall portion includes:

[0006] Step 1: Preset the height of the pier wall, and determine the pressure on the side wall surrounding rock of the traffic tunnel based on the height of the pier wall and the height of the traffic tunnel chamber;

[0007] Step 2: Determine the shear force exerted by the side wall surrounding rock on the pier wall according to the safety factor of the traffic tunnel and the pressure exerted by the side wall surrounding rock of the traffic tunnel;

[0008] Step 3: determining the overturning moment applied by the side wall surrounding rock to the pier wall according to the height of the pier wall and the shear force;

[0009] Step 4: Determine the upper base width and the lower base width of the pier wall portion according to the shear force and the overturning moment.

[0010] Preferably, step 4 is specifically:

[0011] Step 4.1, constructing a first relationship between the shear force and the concrete gravity corresponding to the pier wall portion;

[0012] Step 4.2: construct a second relationship between the overturning moment and the concrete gravity corresponding to the pier wall portion;

[0013] Step 4.3: Determine the upper base width and the lower base width of the pier wall portion according to the first relationship and the second relationship.

[0014] Preferably, step 4.1 is specifically as follows:

[0015] Determine the friction coefficient of the concrete corresponding to the pier wall;

[0016] A first relationship between the product of the concrete weight and the friction coefficient and the shear force is constructed.

[0017] Preferably, the first relationship is:

[0018] The shear force is less than or equal to the product of the concrete weight and the friction coefficient.

[0019] Preferably, step 4.2 is specifically as follows:

[0020] Determine the resisting moment based on the corresponding concrete gravity of the pier wall;

[0021] A second relationship between the overturning moment and the resisting moment is constructed.

[0022] Preferably, the second relationship is:

[0023] The overturning moment is less than or equal to the resisting moment.

[0024] Preferably, the ratio of the height of the pier wall portion to the height of the cavern of the traffic tunnel is 1:5-6.

[0025] Preferably, step 2 is specifically:

[0026] The shear force applied by the side wall surrounding rock to the pier wall is determined based on the product of the safety factor of the traffic tunnel and the pressure on the side wall surrounding rock of the traffic tunnel.

[0027] A second aspect of the present invention provides a bottom support for controlling deformation of surrounding rock in a traffic tunnel, comprising two supporting structures, each supporting structure comprising an integrally connected connecting portion and a pier wall portion;

[0028] The connecting portion is provided on the bottom surface of the traffic tunnel, one end of the connecting portion is connected to the surrounding rock of the side wall of the traffic tunnel, and the other end is connected to the connecting portion of another supporting structure;

[0029] The cross-section of the pier wall portion is a right-angled trapezoid, and the upper base width and lower base width of the pier wall portion are determined according to the above-mentioned method for determining the parameters of the base for controlling the deformation of the surrounding rock of the traffic tunnel; the lower base of the pier wall portion is connected to the upper surface of the connecting portion, and the right-angled side of the pier wall portion is connected to the side wall surrounding rock.

[0030] Preferably, it also includes a through-anchor cable;

[0031] The through-anchor cable is perpendicular to the axis of the traffic tunnel, and one end of the through-anchor cable is connected to the pier wall portion, and the other end passes through the side wall surrounding rock.

[0032] Compared with the prior art, the base support for controlling deformation of surrounding rock in a traffic tunnel and the method for determining its parameters of the present invention have the following beneficial effects:

[0033] The present invention's method for determining parameters for a support for controlling deformation of surrounding rock in a traffic tunnel can determine optimal dimensional parameters for the pier wall, thereby achieving stable support for the traffic tunnel while preventing the support from impacting its use and saving construction costs. The support's connecting portion supports the tunnel's sidewalls, ensuring stability at the pier wall bottom and reducing the tunnel chamber height; the support's upper pier wall portion limits significant deformation of the sidewalls; and the through-anchor cables act as anchor plates, significantly limiting deformation of the sidewalls.

[0034] The parameter determination method of the bottom support for controlling deformation of surrounding rock of a traffic tunnel disclosed by the present invention has a clear concept and clear parameters, is convenient for designers to use, plays a good guiding role, and ensures engineering safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the use status of a traffic tunnel in an embodiment of the present invention.

[0036] Figure 2 This is a flow chart of a method for determining parameters of a bottom support for controlling deformation of surrounding rock in a traffic tunnel according to an embodiment of the present invention.

[0037] Figure 3 Schematic diagram of the overall structure of the base in an embodiment of the present invention.

[0038] Figure 4 Schematic diagram of the structure of the pier wall part in an embodiment of the present invention.

[0039] In the figure: 1 is the main powerhouse; 2 is the water diversion tunnel; 3 is the traffic tunnel; 4 is the connecting part; 5 is the pier wall; 6 is the side wall surrounding rock; 7 is the first pair of through-anchor cables; 8 is the second pair of through-anchor cables. DETAILED DESCRIPTION

[0040] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0041] like Figure 1 As shown, when penstocks are required in the lower horizontal section of the diversion tunnel 2 corresponding to the main powerhouse 1 of a hydropower project, a traffic tunnel 3 is excavated perpendicularly through the diversion tunnel 2 to transport the penstocks. Due to its large diameter and the fact that it intersects with multiple diversion tunnels 2, traffic tunnel 3 is open on both sides. This leads to significant unloading and relaxation of the surrounding rock 6 on the sidewalls, resulting in significant deformation of the sidewalls and cracking of the sprayed layer. Therefore, support for the surrounding rock 6 of traffic tunnel 3 is necessary.

[0042] A first aspect of an embodiment of the present invention provides a method for determining parameters of a support for controlling deformation of surrounding rock in a traffic tunnel, such as Figures 2 to 4 As shown, the bottom support includes a pier wall portion 5 connected to the side wall surrounding rock 6 of the traffic tunnel 3. The cross section of the pier wall portion 5 is a right-angled trapezoid. The method for determining the parameters of the pier wall portion 5 in the bottom support includes:

[0043] Step 1: Preset the height of the pier wall 5 , and according to the height of the pier wall 5 and the height of the chamber of traffic tunnel 3 Determine the pressure on the side wall surrounding rock 6 of traffic tunnel 3 Specifically, the pressure on the side wall rock 6 of the traffic tunnel 3 is determined according to the following formula (1): .

[0044] (1)

[0045] Where, is the rock mass of the side wall surrounding rock 6; is the height of the traffic tunnel 3 (excluding the thickness of the bottom backfill concrete), is the height of the pier wall 5.

[0046] Step 2: Based on the safety factor of traffic tunnel 3 and the pressure on the side wall rock 6 of the traffic tunnel 3 Determine the shear force applied by the side wall rock 6 to the pier wall 5 .

[0047] For example, the shear force applied by the side wall surrounding rock 6 to the pier wall 5 is determined according to the following formula (2): .

[0048] (2)

[0049] Step 3: According to the height of the pier wall 5 and shear force Determine the overturning moment applied by the side wall surrounding rock 6 to the pier wall 5 .

[0050] For example, the overturning moment applied by the side wall surrounding rock 6 to the pier wall 5 is determined according to the following formula (3): .

[0051] (3)

[0052] Step 4: According to shear force and overturning moment Determine the upper base width of the pier wall 5 and bottom width .

[0053] The above step 4 is specifically as follows:

[0054] Step 4.1: Build shear force Concrete gravity corresponding to pier wall 5 The first relationship is:

[0055] Step 4.1.1. Determine the friction coefficient of the concrete corresponding to the pier wall section 5 , , is the friction angle of the concrete corresponding to the pier wall part 5.

[0056] Step 4.1.2: Constructing Concrete Gravity and friction coefficient The product of The first relationship is: shear force Less than or equal to concrete gravity and friction coefficient The product of is shown in formula (4).

[0057] (4)

[0058] The concrete gravity in the above formula (4) is As shown in formula (5).

[0059] (5)

[0060] Where, is the upper base width of the pier wall portion 5; is the lower base width of the pier wall portion 5; is the height of the pier wall portion 5; For concrete weight.

[0061] Step 4.2: Construct overturning moment Concrete gravity corresponding to pier wall 5 The second relationship is:

[0062] Step 4.2.1: According to the concrete gravity of pier wall 5 Determine the resisting moment , as shown in formula (6).

[0063] (6)

[0064] Step 4.2.2: Construct overturning moment and resistance torque The second relationship is: Less than or equal to the resistance moment , as shown in formula (7).

[0065] (7)

[0066] Step 4.3: Determine the upper base width of the pier wall portion 5 based on the first relationship and the second relationship and bottom width Specifically, the upper base width of the pier wall 5 is obtained by combining formula (4) and formula (7) and bottom width .

[0067] The height of the pier wall portion 5 in the embodiment of the present invention is The ratio of the height of the tunnel chamber to the height of the traffic tunnel 3 is 1:5-6, for example, 1:5, 1:5.3, 1:5.5, 1:6, etc.

[0068] For example, the height of the tunnel chamber 3 is , rock mass , concrete weight , the friction angle of the concrete corresponding to the pier wall 5 , safety factor .

[0069] The embodiment of the present invention presets the height of the pier wall portion 5 , then the upper base width of the pier wall 5 is obtained by combining formula (4) and formula (7) and bottom width .

[0070] The embodiment of the present invention can determine the optimal size parameters of the pier wall part 5 through the above-mentioned method for determining the parameters of the base for controlling the deformation of the surrounding rock of the traffic tunnel, thereby achieving stable support for the traffic tunnel 3, avoiding the base affecting the use of the traffic tunnel 3, and saving construction costs.

[0071] The parameter determination method of the bottom support for controlling deformation of surrounding rock of a traffic tunnel disclosed by the present invention has a clear concept and clear parameters, is convenient for designers to use, plays a good guiding role, and ensures engineering safety.

[0072] A second aspect of the embodiment of the present invention provides a support for controlling deformation of surrounding rock in a traffic tunnel, such as Figure 3 and Figure 4 As shown, it includes two supporting structures, each supporting structure includes a connecting portion 4 and a pier wall portion 5 that are integrally connected; wherein the integral connection method can be casting. The above-mentioned connecting portion 4 is arranged on the bottom surface of the traffic tunnel 3, one end of the connecting portion 4 is connected to the side wall surrounding rock 6 of the traffic tunnel 3, and the other end is connected to the connecting portion 4 of another supporting structure; wherein the thickness of the connecting portion 4 is sufficient to meet the shear load under the maximum design tonnage under the transportation condition of the traffic tunnel 3, and the present invention is not limited here. The cross-section of the pier wall portion 5 is a right-angled trapezoid, and the upper base width and the lower base width of the pier wall portion 5 are determined according to the above-mentioned method for determining the parameters of the bottom support for controlling the deformation of the surrounding rock of the traffic tunnel 3; the lower bottom of the pier wall portion 5 is connected to the upper surface of the connecting portion 4, and the right-angled side of the pier wall portion 5 is connected to the side wall surrounding rock 6.

[0073] In order to improve the stability of the surrounding rock at the intersection of the traffic tunnel 3 and the water diversion tunnel 2, the embodiment of the present invention further provides a pair of through-anchor cables, which are denoted as the first pair of through-anchor cables 7. The first pair of through-anchor cables 7 are perpendicular to the axis of the traffic tunnel 3, and one end of the first pair of through-anchor cables 7 is connected to the pier wall portion 5, and the other end passes through the side wall surrounding rock 6. A plurality of first pair of through-anchor cables 7 can be used, and the plurality of first pair of through-anchor cables 7 are arranged in parallel. The embodiment of the present invention also provides a plurality of mutually parallel through-anchor cables, which are denoted as the second pair of through-anchor cables 8, between two adjacent water diversion tunnels 2. The second pair of through-anchor cables 8 are parallel to the axis of the traffic tunnel 3, so that the square surrounding rock area surrounded by the traffic tunnel 3, the water diversion tunnel 2 and the main powerhouse 1 has a mesh of anchor cables to improve the stability of the surrounding rock.

[0074] The base support of the present invention adopts a method of sequential construction on both sides, that is, the support structure on one side is constructed first, and then the support structure on the other side is constructed, so that traffic needs can be well met while controlling the stability of the surrounding rock.

[0075] The connecting portion 4 of the present invention can support the side wall surrounding rock 6 of the traffic tunnel 3, ensure the stability of the pier wall portion 5 and reduce the cavern height (as a safety margin). The upper pier wall portion 5 can limit the large deformation of the side wall surrounding rock 6; the first pair of through-anchor cables 7 can act as an anchor plate, and the effect of limiting the deformation of the side wall surrounding rock 6 is more significant.

[0076] The above merely describes several embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed with the above preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical contents without departing from the scope of the technical solutions of the present application, and the equivalent embodiments are equivalent to the equivalent embodiments, which are within the scope of the technical solutions.

Claims

1. A method for determining parameters of a support for controlling deformation of surrounding rock in a traffic tunnel, characterized in that: The bottom support includes a pier wall portion connected to the side wall surrounding rock of the traffic tunnel. The cross section of the pier wall portion is a right-angled trapezoid. The method for determining the parameters of the pier wall portion includes: Step 1: Preset the height of the pier wall, and determine the pressure on the side wall surrounding rock of the traffic tunnel based on the height of the pier wall and the height of the traffic tunnel chamber; Step 2: Determine the shear force exerted by the side wall surrounding rock on the pier wall according to the safety factor of the traffic tunnel and the pressure exerted by the side wall surrounding rock of the traffic tunnel; Step 3: determining the overturning moment applied by the side wall surrounding rock to the pier wall according to the height of the pier wall and the shear force; Step 4: Determine the upper base width and lower base width of the pier wall portion according to the shear force and the overturning moment, specifically: Step 4.1: Establishing a first relationship between the shear force and the weight of the concrete corresponding to the pier wall portion, specifically: determining the friction coefficient of the concrete corresponding to the pier wall portion; establishing a first relationship between the product of the concrete weight and the friction coefficient and the shear force, wherein the first relationship is: the shear force is less than or equal to the product of the concrete weight and the friction coefficient; Step 4.2: Constructing a second relationship between the overturning moment and the weight of the concrete corresponding to the pier wall, specifically: determining a resistance moment based on the weight of the concrete corresponding to the pier wall; constructing a second relationship between the overturning moment and the resistance moment, wherein the second relationship is: the overturning moment is less than or equal to the resistance moment; Step 4.3: Determine the upper base width and the lower base width of the pier wall portion according to the first relationship and the second relationship.

2. The method for determining parameters of a support for controlling deformation of surrounding rock in a traffic tunnel according to claim 1, characterized in that: The ratio of the height of the pier wall portion to the height of the cavern of the traffic tunnel is 1:5-6.

3. The method for determining parameters of a support for controlling deformation of surrounding rock in a traffic tunnel according to claim 1, characterized in that: Step 2 is as follows: The shear force applied by the side wall surrounding rock to the pier wall is determined based on the product of the safety factor of the traffic tunnel and the pressure on the side wall surrounding rock of the traffic tunnel.

4. A base for controlling deformation of surrounding rock in a traffic tunnel, characterized in that: It comprises two supporting structures, each supporting structure comprises a connecting portion and a pier wall portion which are integrally connected; The connecting portion is provided on the bottom surface of the traffic tunnel, one end of the connecting portion is connected to the surrounding rock of the side wall of the traffic tunnel, and the other end is connected to the connecting portion of another supporting structure; The cross-section of the pier wall portion is a right-angled trapezoid, and the upper base width and lower base width of the pier wall portion are determined according to the parameter determination method of the bottom support for controlling the deformation of the surrounding rock of a traffic tunnel according to any one of claims 1 to 3; the lower base of the pier wall portion is connected to the upper surface of the connecting portion, and the right-angled side of the pier wall portion is connected to the side wall surrounding rock.

5. The support for controlling deformation of surrounding rock of a traffic tunnel according to claim 4, characterized in that: It also includes cross-thread anchor cables; The through-anchor cable is perpendicular to the axis of the traffic tunnel, and one end of the through-anchor cable is connected to the pier wall portion, and the other end passes through the side wall surrounding rock.

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